Fifteen males and fifteen females age 20-36 years will participate in the study to compare the cardiovascular effects of concentric exercise to eccentric exercise on the Biodex Isokinetic Dynamometer. The first part of the study consists of a stress test using the Bruce Protocol to establish maximum oxygen consumption (VO2), blood pressure (BP), heart rate (HR) and perceived exertion (RPE) values. V02, BP, HR, ECG, and RPE data will also be collected during the second part of the study which will be performed on the Biodex. Concentric and eccentric contractions (50% MVC) of the quadriceps muscle of the subject's dominant leg will be performed on the Biodex at speeds of 60 degrees/s and 90 degrees/s. The purpose of this study is to determine if there are significant differences in the cardiovascular parameters between concentric exercise and eccentric exercise as performed on the Biodex. The null hypothesis is that there will be no significant differences in V02, BP, HR, ECG, or RPE for concentric vs. eccentric exercise.